A state of emergency was declared at the Hanford Nuclear Reservation in Richland, Washington after a tunnel collapsed underneath the facility.

Most workers were forced to “take cover” and a manager reportedly sent out an message to employees telling them to “secure ventilation” and “refrain from eating or drinking.” Some were ordered to evacuate immediately while others were told to shelter-in-place as officials investigated the situation.

Tom Carpenter, executive director of Hanford Challenge, a non-profit that monitors the nuclear reservation said plutonium has already been detected in local fish stocks and worries that if changes don’t come soon, wild salmon stocks could be next.

“The Department of Energy informed us this morning that a tunnel was breached that was used to bury radioactive waste from the production of plutonium at the Hanford Nuclear Reservation,” Governor Jay Inslee said in a statement. He went on to say that the White House had already reached out to his office as well.

“This is a serious situation, and ensuring the safety of the workers and the community is the top priority,” Mr Inslee said. “Our understanding is that the site went into immediate lock down, in which workers were told to seek shelter, and all access to the area has been closed.”

The dark area underneath the tall orange flag is the collapse site – a hole left by the tunnel collapse. pic.twitter.com/7fvqsRimhC

The tunnel is said to contain highly contaminated materials including equipment used to transport radioactive fuel rods. A spokesperson said there was no evidence any radioactive materials had been released and all workers in the area were accounted for.

Some interesting factoids about the Hanford site:

According to CBS News, the Hanford Nuclear Reservation was created during World War II to secretly build the atomic bomb. The site produced plutonium for the world’s first atomic explosion and for one of the two atomic bombs that was dropped on Japan.